The need for effective herbicides, both preemergence and postemergence, needs no special emphasis. The control of weeds and undesirable vegetation is of great economic importance since weed competition inhibits the production of foliage, fruits and/or seeds and may reduce the quality of the harvested crop. Weed control is essential for maximum production of many agronomic and horticultural crops including soybeans (Glycine max (L.) Merr.), peanuts (Archis hypogaea L.) and rice (Oryza sativa L.). Furthermore, weeds on noncropped areas may cause a fire hazard, undesirable drifting of sand or snow, or irritation to persons with allergies. Thus, suppression of undesirable weed growth is very advantageous.
Moreover, the need for agricultural chemicals having significant effects on the growth and development of crop plant species is similarly well known. The compounds of this invention are useful as plant growth regulators when employed in amounts effective to regulate the growth of plants, in admixture with a carrier therefor. It will be understood that the term plant as used herein includes plant parts such as foliage, roots, flowers, stems and seeds. Depending on crop, variety, dosage, time of application and certain cultural practices, growth regulating effects which may be obtained include one or more of the following: dwarfing, cessation of terminal growth, inhibition of axillary and intercalary growth, retardation of internode elongation, inhibition of flowering or reproductive development, and the like.
One form of such plant growth regulation which is particularly economically important is the field of harvest aid compounds. The field of harvest aid utilization includes a wide variety of primary effects, including the defoliation of the crop plant; the desiccation of its leaves, stems, and other aerial organs; the control of late-season regrowth (e.g., for cotton); the promotion or inhibition of fruit or flower abscission; the concentration of crop maturity; and the enhancement of consumer-preferred quality factors.
Under normal conditions, many crop plants do not mature uniformly or in a timely fashion that would facilitate an efficient and optimum harvest, either due to equipment scheduling or weather considerations. Crops such as cottom, potato, sunflower, and seed legumes require either desiccation or defoliation before harvest can be effectively accomplished. Thus, for example, when cotton is not defoliated the leaves can interfere with mechanized picking apparati which are frequently employed. Also, leaves can contaminate the cotton lint with trash or green stain, which reduces the quality of the fiber or reduces the efficiency of the ginning process. Likewise, potato vines need to be desiccated for efficient mechanical digging. In addition, upon desiccation of potato leaves and stems, the tuber skin matures and becomes less susceptible to damage from the digger and postharvest handling. Seed legumes and sunflowers are also mechanically harvested, and this process is facilitated if the leaves and stems are removed or desiccated. As with cotton and potato, such defoliation or desiccation also ripens the seed uniformly, accelerates the rate of seed maturation, and conditions the pod or head for easy harvest.
While a large number of compounds possessing herbicidal and/or plant growth regulatory activity are known, it would be nonetheless desirable to possess additional compounds which would effectively control the growth of unwanted vegetation and/or regulate the growth of commercially desirable plants.
U.S. Pat. No. 4,618,365 to Covey et al discloses certain carbamyl-substituted tetrazolinones useful as herbicides. Somewhat similarly, PCT International Application No. PCT/U.S.84/01799 (Theodoridis et al) shows certain phenyl substituted tetrazolinone derivatives which exhibit herbicidal activity.
U.S. Pat. Nos. 3,928,416 to Bayer et al and 4,209,318 to Johnson both show herbicidal 4-trifluoromethyl-nitrodiphenyl ethers. Similar herbicidal diphenyl ethers are disclosed in Chemical Abstracts 94:46981q (1981) (Durr et al); Chemical Abstracts 94; 156539j (1981) (Swithenbank et al); and Chemical Abstracts 95; 150174k (1981) (Barton).
However, neither of these publications suggest that phenoxyphenyl-substituted tetrazolinone derivatives would exhibit herbicidal activity and/or plant growth regulatory activity to a desirable degree.
Accordingly, it is an object of this invention to provide a new class of compounds which exhibit an unexpectedly desirable degree of herbicidal and/or plant growth regulatory activity.
It is another object of this invention to provide novel herbicidal compositions comprising such phenoxyphenyl-substituted tetrazolinones.
It is yet another object of this invention to provide a method for controlling weeds employing such herbicidal compositions.
It is a further object of this invention to provide plant growth regulatory compositions comprising such novel compounds.
It is an additional object of this invention to provide a method for regulating the growth of plants employing such plant growth regulatory compositions.
The above objects and other additional objects will become more fully apparent from the following description and accompanying Examples.